RST series ring stiffness tester is used to determine the ring stiffness of circular cross-section thermoplastic pipes, according customer’s request, it can also execute compression, ring stiffness, ring softness and creep ratio test. This tester meet the requirement of all kinds of plastic pipes, structured-wall pipes, PVC, HDPE, LDPE, PE corrugated pipes, helically wound pipes etc.,
Conform with Standard ISO 9969, ISO 9967.

Feature of RST-1 series:
Suitable for small size pipe test (less 630mm dia.);  computer control, economical type.
 
Principle of ring stiffness: 
The ring stiffness is determined by measuring the force and the deflection while deflecting the pipe at a constant deflection speed.
A cut length of pipe supported horizontally is compressed vertically between two parallel flat platens moved at a constant speed that is dependent upon the diameter of the pipe.
A plot of force versus deflection is generated. The ring stiffness is calculated as a function of the force necessary to produce a 3% diametric deflection of pipe.


Principle of creep ratio: 
A cut length of pipe is placed between two parallel flat horizontal plates and a constant compressive force is applied for 1008 h (42 days). The deflection of the pipe is recorded at specified intervals so as to prepare a plot of pipe deflection against time. The linearity of the data is analysed and the creep ratio is calculated as the ratio between the two years’ extrapolated deflection value and the measured 6 min (0.1 h) deflection.


Other name:
Pipe ring stiffness tester, PVC pipe ring stiffness test, HDPE pipe ring stiffness testing equipment, PE pipe creep rate test, thermoplastic pipe creep ratio test.

^{ISO 9969  "Thermoplastics pipes -- Determination of ring stiffness”
ISO9967  "Thermoplastics pipes -- Determination of creep ratio“}